1. Field of the Invention
The present invention relates to a numeric value changing device and apparatus for use in industrial panel displays and personal computers. More particularly, the invention pertains to a numeric value changing method and apparatus that provide a clear and legible display of a numeric value on a small panel display device and allow ease in making a change to the numeric display without impairing its viewability.
2. Description of the Prior Art
Conventional industrial panel display devices utilize large 10-segment light emitting diodes (LEDs) to ensure that digital display of numeric parameters or the like for process control is legible from a considerable distance.
With recent improvements in liquid crystal displays (LCDs) for smaller size, higher brightness and wider angle of field, it has become possible to use small LCDs for digital display of numeric values set for process control.
With such digital display on the small LCD, the numeric value could be changed or modified using a mouse, touch panel or similar pointing means.
It is customary in the prior art, however, to display numeric changing elements, such as up and down keys and a slide bar, on the display screen of a numeric value changing device and selectively manipulate them by pointing means when to change the numeric value set on the screen.
To change the numeric value by the conventional method, it is necessary to display such display elements as the abovementioned up and down keys and slide bar on the display screen, together with the numeric value. FIGS. 34 and 35 are screen layouts showing examples of the display screen that use the above prior art method. Reference numeral 24 denotes a numeric display area provided on the display surface of a touch panel to display a numeric value of four figures (three in integral part and one decimal place); 27 denotes a slide bar displayed immediately below the numeric display area 24; and 28 denotes up and down keys displayed beside the numeric display area 24. Reference numeral 25 denotes a user's hand, and 26 a selected position pressed by the hand 25. For example, by sliding the user's finger on the slide bar 27, or by pointing the up or down key 28 with the user's finger, the numeric value displayed in the numeric display area 24 can be changed. With the conventional numeric value changing method and apparatus described above, it is necessary to provide on the display screen the display elements (the slide bar and up and down keys) 27 and 28 that are selectively used to change the displayed numeric value, together with the numeric display area 24. Hence, the space for the numeric display area 24 on the display screen is inevitably limited. Consequently, in the case of using a small LCD to provide digital display of a numeric value for use in process control, it may sometimes become impossible to provide a numeric display area large enough to make the display legible from a considerable distance.